Direct absorption imaging of ultracold polar molecules

TL;DR

This paper introduces a direct absorption imaging method for ultracold polar molecules that overcomes the challenge of lacking closed optical transitions, enabling detailed study of molecular quantum gases.

Contribution

The authors develop and systematically characterize a novel absorption imaging technique for ultracold polar molecules near quantum degeneracy.

Findings

Successful imaging of molecular momentum and spatial distributions.

Technique operates at photon shot-noise limit.

Potential to advance studies of molecular quantum gases.

Abstract

We demonstrate a scheme for direct absorption imaging of an ultracold ground-state polar molecular gas near quantum degeneracy. A challenge in imaging molecules is the lack of closed optical cycling transitions. Our technique relies on photon shot-noise limited absorption imaging on a strong bound-bound molecular transition. We present a systematic characterization of this imaging technique. Using this technique combined with time-of-flight (TOF) expansion, we demonstrate the capability to determine momentum and spatial distributions for the molecular gas. We anticipate that this imaging technique will be a powerful tool for studying molecular quantum gases.